Crystal detector



G. A. RCSENFELDER CRYSTAL DETECTOR May 5, 1925. 1,536,974

Filed March 5, 1924 illlll; W 3" I h JEEX i? film GLFosnvFLLmE/i MENTOR ATTORN EY Patented May 5, 1 925.

. cmac-naanosnnmirnm, orrmrsmmen;rsnnsvtvama.

' CRSTAL DETECTOR.

. .applicationqfiled March 3,

To all whom it may; concern:

mann a citizen. of theiUnitedlStates,residing. at Pittsburgh, in the county 'o'f-Alle gheny and State of Pennsylvania, .have .invented inew and useful :Improvements in Crystal Detectors, which the followingis a specification. 1 r

This invention .relatesto detectors, and more particularly to ,a crystal detector -for use in radio receiving sets. J

'One of, the :mainrtbjects of the. invention is to provide adevice' {of this character. in which the (filament cor cats-w.l1isker, or corresponding: element Will be held" in. adjustment after it. has beenlplaced upon a sensitiveq-spotin the crystal of the detector A appear from the detail description.

any suitable 'or preferred electrical insuf urthieriobject is to, rovide. simple and. efli cient means for 'h'ol ing the catswhiskefi in adjustment while: permitting it' to 'be adjusted .when'idesired. Another .object is. to

rovide means whereby the, pressure .on the fi hiskeW may be; regulated for obtainthe bestresults. .Eurtherob'jec-ts will fl' is a "front view of the device .as applied; y i

ig. 2 is. a. entral fverti call section through the device, .011 an-enlargedjscale, parts being shown "inelevation; y g

3 a'sectiontaltensubstantially on line "313 oflF ig. ,1; I f

4 is, a section takengsubsti ntially on line 4-4oif;F ig. 2.

Theidevice includes, aharrel 1 formed ,olI'.

latingmat'erial. A co'llarfil .is secured on theupper end of barrel "1 and is bored and threaded ,for ,recgption of ,a screw plug 2 provided, atits upperfend, with outwardly projecting arms 4-which are secured in any suitable or preferred manner to a disc 5 of electrical insulating material. A cup member 6 is threaded on thelower end of barrel 1, this member being adapted for reception of a mounting 7 fora crystal 8 of galena, or any other suitable or preferred material such as is used for this purpose in crystal receiving sets. I

A brass rod 9 is slidably and rotatably mounted through disc 5 and plug 3 which are suitably bored for this purpose. This rod extends through barrel 1 to within a short distance of the lower end thereof, and

r the lower end of the rod is tapered to procorrespondsfto the feats-whisker employed. in crystalldetectors.

1.924. SerialwNonBSGgGOS.

vide a frusto conical element 10 iW11iQh ieX' tends through a -idownwarcl-ly tapering :openinga provided throughmn annulus 11 seated onua shoulderlQ formed with'inibarrel1 {by reducing the lower portion 13 of bore of the barrel. An expansioncoil spring--14 isnmunted. \aboutirod' 9 and .is zconfinedbetween plug Send a collar 15 .securediiupon the rod substantially centrallythereof. IA second coil spring i 16- ismounted about the lower portion ofrod 9Ha-nd isconfined "-be-. tween I collar 15 and annulus a 1:1. This pro vides a spring mounting for the rod 1Which permits-itrto beadjusted in. either edirection by turning plug (in collar- 2 and theispnings and associated :parts, act toyhold the rod in adjustment As its lower end rod 9,is;;pr-ovided with an angularly disposed contact member. 17 which may befor-med integrally with rod- 9 or .may be tormed-as :a -1separate element and securedto-the rod. lll heomem- I berl7 is preferably veryfine or thinand is adapted to contact with crystal 8,. this member formingn contact element which ,c o-mmon ly I At-itsupper end 1 rod a9 is provided with a a knob 18 secured thereon, this knob being formed of any suitablefior preferred ielectrical insulating material.

The detector constructed in the manner illustratedandv described .is well adaptedgfor use in connection with :spring .conta-cts aC suchas are commonly Jemployedinc nnect-ion with switch boards, .these cont-acts being; positioned and adapted to engage aabout collar '2: and. cup member 6 when. the device is in placepitibeing understoo'dthatthe.eontacts or c'lipsC qare secureduponmpaneL P of a radio receiving set and a re properly connected into-the circuit of'the setby means of wires (1 and d. As the collar 2, plug 3,

spring 14 and rod 9 are all formed of brass or other suitable electrical conducting-.material, and the cup member 6 is also formed of brass, the electrical impulses or current can flow from Wire 01 to member 17, crystal 8, crystal mounting 7, cup member 6 and the lower clip C to wire 03, or vice versa, 9 as will be understood. When the device is applied, by turning rod 9 by means of knob 8, the contact element 17 may be moved over the surface of crystal 8 until this member is positioned upon a sensitive spot in the crystal. After this has been done, the pressure on member 17 may be adjusted by means of plug 3 so as to obtain maximum reception. After the device has been adjusted in the manner described, rod 9 is held in adjustment by the springs and plug and associated parts thus insuring that contact member 17 will not be jarred off of or out of contact with the sensitive spot of the crystal on which it has been placed.

As is known, crystals used in crystal detectors for radio receivers have spots which are more sensitive than other portions of the crystal and it not infrequently happens that considerable trouble is experienced with the type of a detector now in use in placing the cats-whisker on a sensitive spot and keeping it there after this spot has been found. By means of my device, the catswhisker or contact member 17 can be placed upon a sensitive spot of the crystal and, which is of great importance, is etfectually held against casual displacement. This provides a very simple and inexpensive, as well as highly eflicient detector which may be readily applied and used in connection with radio receiving sets of standard construction.

What I claim is 1. In a device of the character described, a barrel of electrical insulating material, a rod of electrical conducting material extending through the barrel, a' crystal supported at one end of the barrel, said rod being provided with a member disposed to contact with the crystal, resilient means for forcing the rod in one direction, resilient means for forcing the rod in the other direction, and positively acting means for exerting pressure on the resilient means for forcing the rod in said other direction.

2. In a device of the character described, a barrel of electrical insulating material, means for supporting a crystal at one end of the barrel, a rod of electrical conducting material extending through the barrel and provided with a contact element disposed to contact with a crystal supported by said crystal supporting means, resilient means for forcing the rod in one direction, resilient means for forcing the rod in the other direction, and means for increasing and diminishing the force acting to move the rod in one direction for adjusting said rod toward or away from the crystal supporting means.

3. In a detector of the character described, a barrel of electrical insulating material, means at one end of the barrel for supporting a crystal, a collar of electrical conducting material secured on the other end of the barrel, a plug of electrical con-ducting material threaded into the collar, an annulus mounted in the barrel remote from the collar and held against movement in a direction away from said collar, a rod of electrical conducting material extending into the barrel and through said plug, said rod being provided within the barrel with an annular collar, an expansion spring mounted about the rod and confined between said plug and the collar of the rod, and an expansion spring mounted about the rod and confined between the collar of the rod and said annulus, the. rod being provided with a contact member disposed to contact with a crystal mounted in said crystal supporting means.

4- In a device of the character described, a barrel of electrical insulating material, a

cup member of electrical conducting material reniovably secured on one end of the barrel, an annulus mounted in the barrel beyond the cup member and held against movement toward the same, a collar of electrical conducting material secured on the other end of th barrel, a plug of electrical conducting material threaded into said-collar, a rod of electrical conducting material extending through said plug and into the barrel, said rod being provided within the barrel with an annular collar, an expansion spring mounted about the rod and confined between the collar thereof and said plug, and an expansion spring mounted about the rod and confined between said annulus and th collar of said rod, the rod being provided at its inner end with an angularly disposed contact element.

In testimony whereof I affix my signature.

enonen A. ROSENFELDER. 

